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<p class="header"><a class="header" href="intro.htm">Orbiter</a> &gt; <a class="header" href="mainmenu.htm">Main menu</a> &gt; <a class="header" href="options.htm">Options</a> &gt; Celestial sphere</p>

<h1>Celestial sphere</h1>

<p>This page provides configuration options for the display of the celestial sphere background.</p>

<h2>Stars rendered as pixels</h2>
<p>Orbiter uses the position, apparent magnitude and spectral class information from the Hipparcos star database (ESA Hipparcos mission)
to render more than 100 000 bright stars as pixels. The settings in this category determine how the apparent magnitude data are mapped to pixel brightness.</p>
<p><ul>
<li>A higher value for the <i>Max. app. magnitude</i> setting increases the render intensity for bright stars, but causes the brightness to saturate at that
apparent magnitude level.</li>
<li>A higher value for the <i>Min. app. magnitude</i> setting increases the render intensity for dim stars, and increases the number of dim stars rendered.</li>
<li>A lower value for the <i>Min brightness</i> setting decreases the render intensity for dim stars, but does not decrease the number of stars rendered.</li>
<li>The <i>magnitude-brightness mapping</i> should be set to <i>exponential</i> for realistic contrast results.</li>
</ul></p>

<h2>Stars rendered as image</h2>
<p>Orbiter can display a starmap image created from Hipparcos and Tycho data on the celestial sphere. This allows for an improved contrast range compared to the
single-pixel rendering.</p>
<p>For best results over all field-of-view settings, turn on both single-pixel and image rendering.</p>

<h2>Background map</h2>
<p>In addition to a starfield image, Orbiter can display a further background image on the celestial sphere. Orbiter ships with a selection of background images.
By default, it displays the Milky Way background generated as a synthetic image with data from the ESA Gaia mission. Alternatively, images from global sky surveys
at different wavelength bands (from infrared to gamma ray) can be displayed for special effects.</p>
<p>The intensity of the background image can be adjusted with the slider.</p>

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